FIG. 1 is a perspective view described in, for example PTL 1, and showing a structure of an associated crimp terminal.
A crimp terminal 101 has such a structure that, in the front portion in the longitudinal direction of a terminal (also the longitudinal direction of a conductor of an electric wire to be connected), there is provided an electrical connection portion 110 to be connected to a terminal of a mating connector side, behind the electrical connection portion 110, there is provided a conductor crimp portion 111 to be crimped to an exposed conductor of an end of an electric wire (not shown), and still behind the conductor crimp portion 111, there is provided a coated crimping portion 112 to be crimped to the electric wire's portion coated with an insulative coating. Between the electrical connection portion 110 and the conductor crimp portion 111, there is provided a first connecting portion 113 for connecting the electrical connection portion 110 with the conductor crimp portion 111. Between the conductor crimp portion 111 and the coated crimping portion 112, there is provided a second connecting portion 114 for connecting the conductor crimp portion 111 with the coated crimping portion 112.
The conductor crimp portion 111, which has a bottom plate 111A and a pair of conductor crimping pieces 111B, 111B provided to extend upwardly from right and left side edges of the bottom plate 111A and to be so crimped as to wrap the conductor of the electric wire positioned on an inner surface of the bottom plate 111A, is formed substantially into a U-shape in cross section. The coated crimping portion 112, which has a bottom plate 112A and a pair of coated crimping pieces 112B, 112B provided to extend upwardly from right and left side edges of the bottom plate 112A and to be so crimped as to wrap an electric wire (a portion with an insulative coating) positioned on an inner surface of the bottom plate 112A, is formed substantially into a U-shape in cross section.
The first connecting portion 113 on the front side of the conductor crimp portion 111 and the second connecting portion 114 on the rear side of the conductor crimp portion 111, which respectively have bottom plates 113A, 114A and low side plates 113B, 114B standing upwardly from right and left side edges of the bottom plates 113A, 114A, are each formed substantially into a U-shape in cross section.
A bottom plate in a range from a bottom plate (not shown) of the electrical connection portion 110 in the front portion to the coated crimping portion 112 in the rearmost portion (the bottom plate 113A of the first connecting portion 113, the bottom plate 111A of the conductor crimp portion 111, the bottom plate 114A of the second connecting portion 114, and the bottom plate 112A of the coated crimping portion 112) is formed continuously in a form of one piece of band plate. The front and rear ends of the low side plate 113B of the first connecting portion 113 are continuous with respective lower half portions at a rear end of a side plate (no reference numeral) of the electrical connection portion 110 and at a front end of the conductor crimping piece 111B of the conductor crimp portion 111, while the front and rear ends of the low side plate 114B of the second connecting portion 114 are continuous with respective lower half portions at a rear end of the conductor crimping piece 111B of the conductor crimp portion 111 and at a front end of the coated crimping piece 112B of the coated crimping portion 112.
Of an inner surface 111R and an outer surface 1115 of the conductor crimp portion 111, the inner surface 111R on a side contacting the conductor of the electric wire is provided with a plurality of serrations 120 each in a form of a recess groove extending in a direction perpendicular to a direction in which the conductor of the electric wire extends (longitudinal direction of the terminal).
FIG. 2 is a detail view of the serrations 120 formed at the inner surface of the conductor crimp portion 111, where FIG. 2(a) is a plan view showing the developed conductor crimp portion 111 and FIG. 2(b) is a cross sectional view taken along the line IIb-IIb in FIG. 2(a), and FIG. 2(c) is an enlarged view of a portion IIc in FIG. 2(b).
The cross sectional configuration of the serration 120 in the form of the recess groove is either rectangular or inverted trapezoidal, where an inner bottom surface 120A is formed substantially parallel to an outer surface 1115 of the conductor crimp portion 111. An inner corner portion 120C where an inner side surface 120B intersects with the inner bottom surface 120A is formed as an angular portion where a plane intersects with a plane. A hole edge 120D where the inner side surface 120B intersects with the inner surface 111R of the conductor crimp portion 111 is formed as an angular edge.
In general, the conductor crimp portion 111 having the above serrations 120 is, as shown in FIG. 3, prepared through a press machining by using a metal mold 200 having protrusion portions 220 (actually, one referred to as serration die assembled to an upper mold of a press metal mold) in positions corresponding to the serrations 120 each in a form of a recess groove.
The metal mold 200 in this case, as shown in FIG. 4, has a protrusion portion 220 which is linear. Therefore, by using a rotary grind stone 250, the metal mold 200 is prepared on an upper surface of a block 210 through a grinding. FIG. 5 shows an external view of the metal mold 200.
For crimping, to the conductor of the end of the electric wire, the conductor crimp portion 111 (of the crimp terminal 101) having the above structure, the crimp terminal 101 is placed on a placing surface (upper surface) of a not-shown lower mold (anvil), then the conductor of the electric wire is inserted between the conductor crimping pieces 111A of the conductor crimp portion 111, and then the conductor of the electric wire is placed on the upper surface of the bottom plate 111A. Then, lowering the upper mold (crimper) relative to the lower mold allows a guide inclined surface of the upper mold to gradually bring down a distal end side of the conductor crimping piece 111B inwardly.
Then, with the upper mold (crimper) further lowered relative to the lower mold, finally, the distal end of the conductor crimping piece 111B is so rounded, with a curved surface continuous from the guide inclined surface to a central mountainous portion of the upper mold, as to be folded back to the conductor side, and the distal ends of the conductor crimping pieces 111B being frictionally mated with each other are made to eat into the conductor, to thereby crimp the conductor crimping piece 111B in such a manner as to wrap the conductor.
The above operations can connect, by the crimping, the conductor crimp portion 111 of the crimp terminal 101 to the conductor of the electric wire. With respect to the coated crimping portion 112 as well, the lower mold and the upper mold are used to gradually bend the coated crimping pieces 112B inwardly, to thereby crimp the coated crimping pieces 112B to the electric wire's portion coated with the insulative coating. By these operations, the crimp terminal 101 can be electrically and mechanically connected to the electric wire.
In the crimp operation by the crimping, an applied pressure force allows the conductor of the electric wire to enter into the serration 120 at the inner surface of the conductor crimp portion 111 while causing a plastic deformation, thus strengthening the joint between the terminal 101 and the electric wire.